Method for measuring area resistance of magneto-resistance effect element

Abstract

A method for measuring an area resistance of a magneto-resistance effect element which includes an upper-barrier layer having a first sheet resistivity Rt, a barrier layer, and a lower-barrier layer having a second sheet resistivity Rb, includes a resistance measurement step, a sheet resistivity measurement step and a establishing step. The resistance measurement step is the step of measuring a resistance R of the magneto-resistance effect element by using predetermined terminals. The sheet resistivity measurement step measures the first sheet resistivity Rt and the second sheet resistivity Rb. The establishing step determines the area resistance RA of the magneto-resistance effect element using the first sheet resistivity Rt, the second sheet resistivity Rb, the resistance R and the intervals among the predetermined terminals.

1 . A method for measuring an area resistance of a magneto-resistance effect element which includes an upper-barrier layer having a first sheet resistivity Rt, a barrier layer, and a lower-barrier layer having a second sheet resistivity Rb, comprising the steps of:
 a resistance measurement step of measuring a resistance resistance R of the magneto-resistance effect element by using predetermined terminals;   a sheet resistivity measurement step of measuring the first sheet resistivity Rt and the second sheet resistivity Rb; and   a establishing step of establishing the area resistance RA of the magneto-resistance effect element by using said first sheet resistivity Rt, said second sheet resistivity Rb, said resistance R and the intervals among said predetermined terminals.   
     
     
         2 . The method for measuring an area resistance of a magneto-resistance effect element according to  claim 1 ,
 wherein said sheet resistivity measurement step comprises:   calculating a ratio α of the second sheet resistivity Rb to the first sheet resistivity Rt;   measuring a parallel resultant resistance Rs of the sheet resistivities Rt and Rb in the magneto-resistance effect element, by a four-terminal measurement method; and   calculating the first sheet resistivity Rt and the second sheet resistivity Rb as Rt=((1+α)/α)×Rs and Rb=(1+α)×Rs, respectively, by using the ratio α and the parallel resultant resistance Rs.   
     
     
         3 . The method for measuring an area resistance of a magneto-resistance effect element according to  claim 2 ,
 wherein said step of calculating the ratio α comprises:   the step of forming a first film having only an upper-barrier layer and a second film having only a lower-barrier layer, respectively;   the step of measuring a sheet resistivity Rto of the first film and a sheet resistivity Rbo of the second film by the four-terminal measurement method, respectively; and   the step of calculating the ratio α as α=Rbo/Rto.   
     
     
         4 . The method for measuring an area resistance of a magneto-resistance effect element according to  claim 2 ,
 wherein the magneto-resistance effect element includes a first underlayer and a second underlayer between which a first conductive layer is interposed, and a first cap layer and a second cap layer between which a second conductive layer is interposed; and   said step of calculating the ratio α is the step of calculating the ratio α as α=Db/Dt by using a thickness Db of the first conductive layer and a thickness Dt of the second conductive layer.   
     
     
         5 . The method for measuring an area resistance of a magneto-resistance effect element according to  claim 1 ,
 wherein said sheet resistivity measurement step comprises:   the step of measuring the resistance R in the magneto-resistance effect element, a plurality of number of times by a CIPT method;   the step of establishing the first sheet resistivity Rt and the second sheet resistivity Rb by using the resistance R; and   the step of calculating the average values measured a plurality of number of times, as the first sheet resistivity Rt and the second sheet resistivity Rb.